An articulated rod is generally provided with two segments rotatably connected together at a first end. The second end of one of the two segments is connected to a fixed wall. The second end of the second segment is then connected to a moving wall, the moving wall thus being capable of being displaced relative to the fixed wall by simply extending and retracting the articulated rod.
In the case of a hatch, for example, the first segment of the articulated rod is mounted on the wall bounding the cavity of the hatch, whilst the second segment is rotatably mounted on the door of the hatch which must be opened and closed. In the retracted position of the rod the two segments extend one beside the other and the door covers the opening of the hatch. In the extended position of the rod the two segments extend in the direction of their mutual extension. The door does not obstruct the opening of the hatch.
In order to maintain the hatch in the open position a method is known for locking the articulated rod so that the said articulated rod does not retract accidentally or in an untimely manner.
To achieve this the locking device normally used tends to lock the articulated rod at the joint between the two segments of the articulated rod. More precisely, a sliding piece is mounted translatorily about one of the two segments of the rod, and when the two segments extend in the direction of mutual extension the sliding piece is slid in the direction of the connection between the two segments. Once the sliding piece is level with the articulated joint between the two segments, and to the extent that the contour of the sliding piece more or less follows the contour of the two segments at the said joint, the articulated rod can no longer be retracted. When the articulated rod is to be retracted again it is sufficient to slide the sliding piece along one of the two segments so as to release the articulated joint. It is then possible to retract the articulated rod.
The locking device of prior art is of simple design since it is formed from a tubular piece having a diameter that is slightly larger than the diameter of the two segments of the rod.
However, such a locking device only allows an articulated rod to be locked in the extended position. Moreover, when it is necessary to maintain the articulated rod not in the extended but in the retracted position, the locking device of prior art is not transposable. Furthermore, because of the presence of the lockable articulated joint of prior art, the extension of such an articulated rod does not have perfect kinematics. Such an articulated rod does not therefore give entire satisfaction in a confined space. For example, the articulated joint may knock uncontrollably against the walls of a hatch of small volume.